In particular, the present invention relates to an actuating assembly, for example of the type illustrated in FIG. 1A, for displacing a general operative member according with a roto-translation motion, and in the particular example described for displacing a funnel, or a baffle, or even a blowing head of a glassware forming I.S. machine, respectively to convey a gob of glass into a glassware forming mold, to close an upper inlet opening of the forming mold itself and to blow air into the inner cavity of the glassware being formed and make it assume the final shape.
The aforementioned roto-translation motion is obtained by combining a translation along a vertical axis to and from the forming mold and a rotation about the vertical axis itself from and to an operative position, in which the baffle, the funnel, or the blowing head are coupled to the forming mold.
Specifically, in FIG. 1A, reference G indicates a generic known actuating assembly, which extends through a box L of the machine and comprises a fixed frame T, a supporting shaft M of the operative member N coupled to the fixed frame coaxially to the vertical axis, a linear actuator B for translating the shaft along the vertical axis, a cam and tappet device C for rotating the shaft about the vertical axis itself arranged under the linear actuator B and a hydraulic damping cartridge D for braking the operative member when it is arranged near its raised end-of-stroke position along the vertical axis. The damping along the stretch near the lowered end-of-stroke position, on the other hand, is performed by controlling the pneumatic actuator and varying, for example, the compressed air exhaust passage section.
The hydraulic damping cartridge is arranged over, and in all cases near the linear actuator, and in some cases, like in the illustrated case, also near the box, and is connected to a dedicated hydraulic circuit H thereof external to the assembly.
On the other hand, the tappet and cam device is arranged under the linear actuator and comprises a fixed cam defined by a groove obtained in a side wall of a tubular body and a tappet element radially overhanging from a lower free end portion of the shaft and plunging into the tubular body.
The cam device is lubricated by the lubricating oil contained in a variable-volume chamber, and upper inlet of which is crossed by the mentioned end portion which is, in turn, coupled to the tubular body itself by the interposition of a seal surrounding the end portion itself.
Although universally used, the known actuator assemblies of the type described above are not very satisfactory both from the functional point of view and with regards to working environment safety.
This is consequent in part to the type of damping cartridges used, and specifically because they must be fed by a dedicated, external operative liquid circuit, the operative liquid notoriously having a high degree of flammability.
Although insulating heat barriers are provided, the external circuit is in all cases arranged in a high temperature environment by effect of the proximity with the molds, and consequently in a very dangerous environment in case of leakages or sudden failures which often generate fire aboard the machine.
This dangerousness is then accentuated if the cartridge is also arranged outside the box and closer to the molds.
Furthermore, by effect of the arrangement of the cam and tappet device on the lower end of the assembly, during the upward and downward movements of the shaft, the plunging end portion of the shaft itself generates significant variations of pressure and volume in the mentioned chamber in which the lubricating oil is present, thus inevitably triggering pumping phenomena, which leads to a gradual emptying of the chamber because the oil exits through the seal and, by moving up the shaft, enters into the pneumatic cylinder in some cases, and leaks outside the assembly in others.
In addition, the arrangement of the tappet element on the plunging free end of the shaft and the limited available space make it impossible to support the radial loads transmitted to the shaft by the tappet element itself by means of supporting bearings and/or bushings, so that the end part of the shaft always works in overhanging manner, with inevitable anomalous wear of the cam/tappet assembly.